There's no mention of sharding whatsoever. Without that this has very little to do with Planetscale and is much closer to your average managed DB (RDS etc.). There's also no mention of a bouncer/gateway/reverse proxy, which is necessary for zero downtime.

I get that Planetscale hosts "vanilla" Postgres instances but naturally those are limited by single instance size limits. I imagine this is predominantly a marketing strategy for them, acting as a funnel for their sharding products.

But perhaps that's the goal with this project, to not be Planetscale at all, and to focus on the single node. If that's the case, then great, best of luck, but the roadmap is missing some important pieces for me to take this seriously. In either case I find drawing comparison with Planetscale to not be very helpful or illustrative of the project and its goals.